How to make Lye
Lutefisk
Lard obviously comes from butchering animals and devs have mentioned adding this before.
Now here's where it gets stupid!
Boil your lard in a cauldron and take the lye-water and add it to teh boiling fat. After cooking for a stick or two the fire is put out and the hot cauldron will saponify. When it cools the glycerin will seperate from the soap you have made.
Nitrate crystals can be had by pouring water over a bottomless bucket with a linen sieve attatched to the bottom. Ash, straw, manure, & dirt are composted for about two weeks in game (Realistically: 1 year) and placed into the bucket for this leeching. The leeched water is boiled off slowly and when it's gone the nitrate crystals can be harvested from the bottom. This is added to the glycerin above, or directly to wood ash. The former gives nitroglycerin and the latter gives gunpowder.
The explosives could be used in the removal of buildings and soap should be used for the removal of scent tricks applied for hunting which have been suggested multpile times elsewhere to reapply a different hunting scent.